"""From http://sebsauvage.net/python/gui/"""

import tkinter as tk


class my_tk_app(tk.Tk):
    """This class holds the main window"""

    def __init__(self, parent):
        """We use the parent constructor and keep track of our parent"""
        tk.Tk.__init__(self, parent)
        self.parent = parent
        self.initialise()

    def initialise(self):
        """To separate GUI from logic, we create widgets here"""
        # Create the layout manager
        self.grid()
        
        # Create and keep a reference to a text entry
        self.entryVariable = tk.StringVar()
        self.entry = tk.Entry(self, textvariable=self.entryVariable)
        self.entry.grid(column=0, row=0, sticky='EW')
        self.entry.bind("<Return>", self.OnPressEnter)
        self.entryVariable.set(u"Entrez du texte ici.")
        
        # Create a button
        button = tk.Button(self, text=u"Cliques moi !",
                           command=self.OnButtonClick)
        button.grid(column=1, row=0)
        
        # Create a label
        self.labelVariable = tk.StringVar()
        label = tk.Label(self, textvariable=self.labelVariable,
                         anchor='w', fg='white', bg='blue')
        label.grid(column=0, row=1, columnspan=2, sticky='EW')
        self.labelVariable.set(u"Salut !")

        # Allow content to be resized with window
        self.grid_columnconfigure(0, weight=1)
        # Enable resizing horizontally, not vertically
        self.resizable(True, False)

        # tk will change win size according to content
        # so we update to compute size, and we fix it
        self.update()
        self.geometry(self.geometry())   

        # Default focus to the text entry
        self.entry.focus_set()
        self.entry.selection_range(0, tk.END)

    def OnButtonClick(self):
        self.labelVariable.set(self.entryVariable.get() + " (bouton)")
        self.entry.focus_set()
        self.entry.selection_range(0, tk.END)

    def OnPressEnter(self, event):
        self.labelVariable.set(self.entryVariable.get() + " (entrée)")
        self.entry.focus_set()
        self.entry.selection_range(0, tk.END)


if __name__ == "__main__":
    app = my_tk_app(None)
    app.title("My tkinter application")
    app.mainloop()